A liquid crystal display usually comprises a liquid crystal panel and a backlight module, wherein the backlight module mainly functions to provide a surface light source required for the liquid crystal panel to display. Generally, depending on the position of the light source, the backlight module can be divided into direct type and edge-lit type. The light source of the direct type backlight module is disposed directly below the backlight module, usually for a liquid crystal display of large size, and the light source of the edge-lit type backlight module is disposed at a side of the backlight module, usually for a liquid crystal display of small size.
In order to prevent non-uniform brightness formed on a liquid crystal display, an optical film is generally used to uniformize the brightness of the entire images and to maintain the entire images brightness without compromising the light source brightness. Optical films are mainly used in the existing technology to achieve the purpose of light uniformization and concentration. However, phenomena such as deformation (shrinkage) of an optical film and blue light leakage caused by the disposition of the optical film and the light source and the distance therebetween all result in poor brightness uniformity of images in the existing methods. Therefore, how to maintain the brightness uniformity of images is the theme for researching at present.